The present invention relates in particular to a carrier element for a window lifting device.
In particular in the case of motor-vehicle window lifting devices it is known for a carrier element which is connected to the glass which is to be adjusted to be displaceably guided along at least one guide rail of the window lifting device. The entrainment catch herein by way of a traction means, for example a cable pull, is coupled to a drive installation, so as to transmit a driving force and to adjust the carrier element along the guide rail. On account thereof, the glass is then displaced, for example lifted or lowered, along a predefined adjustment path.
A carrier element for a window lifting device of this type is usually produced from a plastics material or from a plurality of plastics materials. Herein it is known for the carrier element to be embodied in multiple parts such that various components which are optimized in terms of specific functions are produced separately from one another and are interconnected. For example, it is known for a main body of the carrier element, which for transmitting a driving force is coupleable to a traction means of the window lifting device, to be produced from a first material which has a comparatively high strength, such as polyamide, for example. A sliding body is then often push-fitted, in particular clip-fitted, to this main body, said sliding body being produced from a friction-optimized material such as polyoxymethylene (POM for short), for example. The carrier element later bears on the guide rail by way of this sliding body so that the material pairing between the sliding body of the carrier element and the guide rail is decisive for minimizing the friction which arises when the carrier element is displaced along the guide rail. By using a separate sliding body, the carrier element has a friction-optimized portion only in a localized manner, and it is not necessary for the carrier element to have to be produced entirely from the expensive friction-reducing material.
In order for the assembly effort to be reduced it is further known for the carrier element for a window lifting device to be produced by a multicomponent injection-molding method, so as not to produce individual bodies of the carrier element that are provided for dissimilar functions separately from one another and subsequently have to assemble said bodies. In this way, it is known, for example, for a soft component, for example an elastomer, to be molded to a main body of a carrier element, so as to configure in a targeted manner a damping stop in a portion of the carrier element and/or to provide a certain degree of elasticity. For example, the soft component is molded to a region of the main body of the carrier element by way of which the carrier element impacts on a stationary component, so as to predefine a lowermost or an uppermost adjustment position of the glasses. Furthermore, it is known from WO 2006/024267 A1 for a support body from a soft component to be configured in a multicomponent injection-molding method on a guide region of a carrier element by way of which the carrier element is mounted on a guide rail, so that by way of this support body—which in comparison with the contiguous material is more elastic—the position of the window glass which is connected to the carrier element may be more easily adapted to the guide rail, so as to compensate for tolerances.
In the case of the production methods for such a carrier element that have hitherto been implemented in practice, various bodies which in term of the geometry thereof and the material used are adapted to their respective function are molded in the multicomponent injection-molding method in a classic hard-to-soft sequence. In other words, herein always the material melting at a higher temperature, polyamide for example, is processed first, and subsequently a material melting at a lower temperature, POM for example, or a soft component, is processed.
In this way, it is described by way of example also in DE 102 07 140 B4 that a sliding body from a material having good sliding properties is molded to a main body of a carrier element from a material of relatively high strength.
In an analogous manner, DE 100 27 877 A1 describes the production of a carrier element of dissimilar materials according to the insertion technique, wherein a main body and a mount for connecting to a window glass are molded to at least one prefabricated connection element, so that the mount by way of the at least one connection element is repositionable in relation to the main body.
The previously known production processes may have the disadvantage that the adhesion of the material melting at a lower temperature is not at an optimum and, by way of so-called interlinking features or rearward-engaging features it has to be ensured that the two sequentially molded bodies are interconnected with adequate strength.
Additionally, sealing of the injection-molding die used may be difficult since the dissimilar bodies are usually made from the outside toward the inside. For example, the main body from the material melting at a higher temperature is initially molded, and a body from a material melting at a lower temperature is subsequently molded in the interior of said main body and/or in regions lying inside said main body. In practice, excessive injection often arises here despite sealing edges, or scuffing arises in critical regions, contaminating the injection-molding tool and thus causing the formation of burrs. By virtue of excessive injection which is often smooth, stick-slip effects and thus undesirable noise generation may moreover arise during use of the window lifting device in combination with the glass.
Here too, it has hitherto been hardly possible for material to be saved when a soft component has been used for producing a damper body on a main body of a carrier element. By virtue of long flow paths and of the sublayer which is formed by the (plastics) material of the already molded main body, a reduction in the wall thickness of the soft component is not possible. Excessive injection pressures would arise, in the case of which the formation of burrs significantly increases. Moreover, by way of the necessary modification to the sealing edges the closing-force requirement of the injection-molding plant would be increased, the formation of burrs becoming more probable on account thereof.